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US3964736A - Helical extension spring and method of making same - Google Patents

Helical extension spring and method of making same Download PDF

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Publication number
US3964736A
US3964736A US05/475,805 US47580574A US3964736A US 3964736 A US3964736 A US 3964736A US 47580574 A US47580574 A US 47580574A US 3964736 A US3964736 A US 3964736A
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US
United States
Prior art keywords
spring
wire
spring body
force
eyelet
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US05/475,805
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English (en)
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Joachim Walter Gerhard Huhnen
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F1/00—Springs
    • F16F1/02—Springs made of steel or other material having low internal friction; Wound, torsion, leaf, cup, ring or the like springs, the material of the spring not being relevant
    • F16F1/04—Wound springs
    • F16F1/12—Attachments or mountings
    • F16F1/123—Attachments or mountings characterised by the ends of the spring being specially adapted, e.g. to form an eye for engagement with a radial insert
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21F—WORKING OR PROCESSING OF METAL WIRE
    • B21F35/00—Making springs from wire
    • B21F35/02—Bending or deforming ends of coil springs to special shape

Definitions

  • This invention relates to a helical extension spring with a spring body and two eyelets or loops formed integrally with the body, the free ends of the eyelets touching the two end coils of the spring body; the invention also relates to a method of making such spring.
  • the eyelets on the spring body are manufactured by bending a half coil up to two coils of the spring body to form each eyelet.
  • the pre-stress forces in the eyelets which are formed of a half loop attain in the maximum case the value of the pre-stress forces which can be produced with conventional coiling and winding methods in the spring body; the pre-stress forces in eyelets consisting of one to two coils are, by comparison, even smaller.
  • pre-stress force means that force which acts in the direction along the longitudinal axis of the spring, such force causing a lifting-off of the wire ends or full eyelet coils from the adjacent end coil of the spring body.
  • pre-stress forces are purely accidentally created and there is no teaching in the state of the art of spring manufacture according to which this pre-stress force may be utilized for the attainment of any particular effects.
  • Many times these pre-stress forces are almost zero, and furthermore there are many cases in which the complete loops or eyelets or the wire ends lie at a predetermined accurate distance from the spring body. This is especially the case with loops or eyelets which are formed from a half coil of the spring body.
  • the alternating bending stress at the eyelet-root is always approximately 1.5 times as big as the bending fatigue strength of the spring-wire when the spring body is stressed up to its torsional fatigue strength.
  • the much larger wire length of the spring body in comparison to the length of the wire in the loop or eyelet, can never be used to its full working capacity.
  • the only way in which the spring body of a conventional helical tension spring can be employed to its full fatigue strength is by making the end coils on the spring body with a coil diameter which is approximately two-thirds of the coil diameters of the remaining coils of the spring body, and make the eyelet or loop of the spring with such decreased diameter.
  • the invention has among its objects the provision of a helical extension spring with low-built or shaped eyelets or end loops, whose fatigue strength is at least as large as the fatigue strength of the spring body, and which contribute as little as possible to the deflection of the spring, as well as a method for the making of such spring.
  • These objects are attained by providing a spring into each eyelet or end loop of which there is built-in an initial force which exceeds the force necessary to lift off the adjacent coils of the spring body, such initial force being larger than the force supplied to the eyelets or loops, which produces a torsional stress in the spring body which amounts to a tenth of the tensile strength of the spring wire from which the spring is formed.
  • one wire section is formed in a plane disposed approximately normal to the longitudinal axis of the spring body, and this wire as a whole is bent approximately in a plane containing the axis of the spring body, the wire sections thereafter being plastically and elastically deformed into eyelets at least by tensile forces being applied in the middle of the wire section approximately in the direction of the longitudinal axis of the spring body, such eyelets elastically bearing upon the end coils of the spring body.
  • the wound-in pre-stress of the spring body amounts to 10% of the tensile strength of the spring wire; as already mentioned maximally conventional eyelets can abut the spring body with a force which corresponds to such pre-stress.
  • the helical extension spring according to the present invention has the bent-in initial pre-stress force of each eyelet deliberately larger than the wound-in pre-stress force of the spring body, and, as a matter of fact as large as possible. It is thereby assured that the life of the eyelets is equal to the fatigue life of the spring body by decreasing the alternating stress at the eyelets.
  • the eyelets under working conditions are deformed so that they constitute only a negligibly small spring deflection before the lift-off of the ends of the eyelets from the end coils of the spring body.
  • the helical extension spring of the invention permits the utilization of the total working capacity of the spring body, which increases its importance with an increase in the number of coils which the spring body has, because in such a case the wire length of the eyelets, which in general dictate the fatigue life of the spring, amount to only a fraction of the total wire length.
  • the process according to the invention can be carried out with or without intermediate heat treatment, which maybe, depending on the material used, an annealing or hardening or tempering.
  • intermediate heat treatment which maybe, depending on the material used, an annealing or hardening or tempering.
  • the first preferred embodiment of the process of the invention which is particularly suitable for the manufacture of springs with middle or large ratios of the diameter of the end coils to the diameter of the spring wire, it is provided, that a straight, tangentially extending shank of the wire section is formed, and that each shank at its starting point is angularly bent into a position in which it extends along a diameter transversely over the adjacent end coil, and that each of the angularly bent shanks at its free end portion and at the starting point is held in abutment with the adjacent end coil, as long as the pulling force acts on it.
  • the forming and angular bending of the shanks can be carried out in one step with the manufacture of the spring body.
  • FIGS. 1 to 9, inclusive, illustrate a first embodiment of the method and the pre-stages thereof
  • FIG. 10 illustrates a variation of the first embodiment
  • FIGS. 11 to 13 illustrate a second variation of the method and its pre-stages
  • FIGS. 14 to 16 illustrate a third variation of the method in its pre-stages
  • FIG. 17 is a so-called "Woehler-graph" in which the Woehler-lines for a conventional helical extension spring are shown in dash lines and the Woehler-lines for a helical extension spring in accordance with the invention are illustrated in solid lines; and
  • FIG. 18 illustrates the loading of the eyelets for springs according to the present invention as well as for conventional springs; at the left-hand portion of this figure there is shown the loading of twist wound springs with a high mean stress and slow stress range, and at the right hand portion of the figure there is shown the loading for normally wound springs with smaller mean stress and high stress range.
  • FIGS. 1 and 2 show two side views shifted 90° with respect to each other
  • FIG. 3 is a top view in the direction of the arrow A of the end of a spring body of a first embodiment. Onto such spring body there is bent a straight, tangentially extending shank 11.
  • FIG. 3 schematically illustrates the jaws 12 and 13 of a clamping device and a ram 14 for angularly bending the shank 11.
  • FIGS. 4 to 6 illustrate in the same types of views as FIGS. 1 to 3, incl., respectively, the same end of the spring body after the angular bending of the shank 11 at its starting point in a position in which it extends along a diameter transversely over the adjacent end coil 9 and thereby forms a bridge or cross piece 21.
  • the angular bent shank 11, or now the cross piece 21 at its free end section, toward which the arrow 23 points, and at the starting point, which is indicated by the arrow 22, is held in abutment with the adjacent end coil 9 of the spring body and furthermore is deformed into an eyelet 31 by means of a tension or pulling force acting approximately in the direction of the arrow 26, being exerted substantially in the middle of the cross piece 21, said tensional or pull force being applied by a hook-shaped tool 25.
  • FIGS. 7 to 9 illustrate the same end of the spring again in the same views as FIGS. 1 to 3, incl., after the plastic and elastic deformation of the corss piece 21 into an eyelet 31.
  • the upper illustrated half of the eyelet 31 is pulled first of all during the plastic and elastic deformation of the root section 32 into the position 33. If the free eyelet end 34 were not simultaneously held in abutting contact against the end coil 9, then the eyelet 31 could, for example, elastically snap back through the illustrated angle ⁇ .
  • FIG. 10 A first variant of the invention is shown in FIG. 10, which corresponds generally to FIG. 8.
  • This variant essentially corresponds in most other respects to the embodiment of FIGS. 1 to 9.
  • both halves of the eyelet 40 have bent portions 41, respectively 42 abutting against the spring body.
  • Such bent portions are created during the deformation of the cross piece under tensional force.
  • the advantage of the bent portions 41 and 42 resides in that they contribute to the pre-stress force, in view of their elastic deformation, with which the lower half of the eyelet 40 abuts against the spring body.
  • FIGS. 11 to 13, incl. illustrate respectively a top view and two side views of one end of the spring body 10 of the second embodiment, at the end coil 50 of which there is formed a wire section 51 which is more moderately bent (less curvature).
  • FIG. 12 illustrates the condition after the angular bending of the wire section 51 about 90° at the position 58, which condition is illustrated in dashed lines in FIG. 11. In this condition the wire section 51 is situated in a plane 59 which contains also the axis 52, whereby the free wire end 53 is located after the angular bending behind a plane 54 adjacent to the spring body 10, said plane being determined by the adjacent coil 50.
  • FIG. 11 illustrate respectively a top view and two side views of one end of the spring body 10 of the second embodiment, at the end coil 50 of which there is formed a wire section 51 which is more moderately bent (less curvature).
  • FIG. 12 illustrates the condition after the angular bending of the wire section 51 about 90° at the position 58, which condition is illustrated in
  • FIG. 13 illustrates the final condition of the eyelet after the deforming by means of a pulling force and the simultaneous squeezing together of the wire end sections 51 as well as the following putting the wire end 53 into abutment with the end loop 50.
  • the greatest deformation occurs in the sections 55 and 56.
  • the elastic pre-tension force is, however, principally created by the root section 56.
  • the third embodiment illustrated by FIGS. 14 to 16, incl., is manufactured in a very similar manner.
  • the wire end section 61 is more strongly bent than the end 60 coil in such manner that; the wire end section 61, which exhibits at first the bending of the end coil at the position 67, is buckled inwardly at the position 67 and a widening of the bent wire end section 61 takes place.
  • This is again accompanied by a simultaneous deformation of the bent wire end section by means of a pulling force.
  • the two Woehler-lines in FIG. 17 respectively illustrate the dependency of the linearly traced torsional stress range ⁇ h for the spring body shown as the ordinate with the number of cycles to failure N of the eyelets drawn logarithmically on the absissca cycles to.
  • the region of fatigue strength for finite life that is the region I lying to the left of the breaking point of the Woehler line as well as the region II of fatigue strength on the right of the breaking point in case of the helical tension spring of this invention is substantially larger than those of the conventional helical springs.
  • the fatigue strength is from 30% to 50% higher as those with the conventional springs.
  • FIG. 18 illustrates the loading of the eyelets with springs of this invention as well as with conventional drill wound springs, and in fact, on the left for twist wound springs with a high means stress ⁇ 3 + ⁇ 1 )/2 and slow stress range and on the right for normally wound springs with smaller mean stress and high stress range; for instance ##EQU1## the mean stresses are not shown as lines in FIG. 18 with a view to clearness of the figure, ⁇ 3 is the symbol for the permissible maximum stress of the spring material.
  • the dependency of the alternating stress ⁇ b at the eyelet root to the time t is illustrated with dash lines for conventional springs and with full lines for helical tension springs in accordance with the invention.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Springs (AREA)
  • Wire Processing (AREA)
US05/475,805 1973-06-01 1974-06-03 Helical extension spring and method of making same Expired - Lifetime US3964736A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2327796A DE2327796C3 (de) 1973-06-01 1973-06-01 Verfahren zum Herstellen von ösen an Schraubenzugfedern
DT2327796 1973-06-01

Publications (1)

Publication Number Publication Date
US3964736A true US3964736A (en) 1976-06-22

Family

ID=5882684

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/475,805 Expired - Lifetime US3964736A (en) 1973-06-01 1974-06-03 Helical extension spring and method of making same

Country Status (13)

Country Link
US (1) US3964736A (xx)
JP (1) JPS5537655B2 (xx)
AT (1) AT337501B (xx)
BE (1) BE815882A (xx)
BR (1) BR7404521D0 (xx)
CH (1) CH584367A5 (xx)
DE (1) DE2327796C3 (xx)
DK (1) DK293874A (xx)
FR (1) FR2231892B1 (xx)
GB (1) GB1470076A (xx)
IT (1) IT1013830B (xx)
NL (1) NL163146C (xx)
SE (1) SE7407246L (xx)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0041095A1 (en) * 1980-05-30 1981-12-09 International Business Machines Corporation Method for operating a spring in a flat rate mode particularly adapted for typewriter ribbon cartridges
WO2002094473A1 (en) * 2001-05-22 2002-11-28 Canimex Inc. Device for bending an extremity of a torsional spring
US20040029457A1 (en) * 2001-08-07 2004-02-12 Martin Jourdan Contact element for an electrical plug connection
US6857666B1 (en) 2002-07-18 2005-02-22 Jerry L. Ashlock Spring and apparatus for its use
US20100262189A1 (en) * 2006-09-07 2010-10-14 Kyung-Woo Park Flexible rod manufacturing apparatus and method for a spinal fixation and the flexible rod manufactured through the same
US20210324930A1 (en) * 2016-04-13 2021-10-21 Suncall Corporation Coil spring

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3041833A1 (de) * 1980-11-06 1982-06-09 Robert Bosch Gmbh, 7000 Stuttgart Anordnung zur zugfederaufhaengung
JPS5797253U (xx) * 1980-12-04 1982-06-15
FR2513698A1 (fr) * 1981-09-30 1983-04-01 Sibe Procede et installation de controle en place de carburateurs
CN110681807B (zh) * 2019-08-27 2021-06-29 泰州市苏源汽车配件有限公司 一种应用于显示屏转向系统的弹簧卷曲成型处理工艺
CN112547988B (zh) * 2020-11-20 2023-03-17 昌河飞机工业（集团）有限责任公司 一种制造初拉力弹簧的方法和装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US924724A (en) * 1908-07-07 1909-06-15 John W Benson Spring-wheel.
DE606718C (de) * 1934-12-08 Siemens Schuckertwerke Akt Ges Zugfeder
US2040656A (en) * 1934-11-06 1936-05-12 Bunting Glider Company Spring construction
US2524293A (en) * 1948-09-25 1950-10-03 Westinghouse Electric Corp Tension spring
US3292884A (en) * 1965-05-27 1966-12-20 Gen Electric Hermetic compressor mounting system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE606718C (de) * 1934-12-08 Siemens Schuckertwerke Akt Ges Zugfeder
US924724A (en) * 1908-07-07 1909-06-15 John W Benson Spring-wheel.
US2040656A (en) * 1934-11-06 1936-05-12 Bunting Glider Company Spring construction
US2524293A (en) * 1948-09-25 1950-10-03 Westinghouse Electric Corp Tension spring
US3292884A (en) * 1965-05-27 1966-12-20 Gen Electric Hermetic compressor mounting system

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0041095A1 (en) * 1980-05-30 1981-12-09 International Business Machines Corporation Method for operating a spring in a flat rate mode particularly adapted for typewriter ribbon cartridges
US4367052A (en) * 1980-05-30 1983-01-04 International Business Machines Corporation Flat rate spring particularly adapted for typewriter cartridges
WO2002094473A1 (en) * 2001-05-22 2002-11-28 Canimex Inc. Device for bending an extremity of a torsional spring
US6681809B2 (en) 2001-05-22 2004-01-27 Canimex Inc. Device for bending an extremity of a torsional spring
US20040029457A1 (en) * 2001-08-07 2004-02-12 Martin Jourdan Contact element for an electrical plug connection
US6857666B1 (en) 2002-07-18 2005-02-22 Jerry L. Ashlock Spring and apparatus for its use
US20100262189A1 (en) * 2006-09-07 2010-10-14 Kyung-Woo Park Flexible rod manufacturing apparatus and method for a spinal fixation and the flexible rod manufactured through the same
US20210324930A1 (en) * 2016-04-13 2021-10-21 Suncall Corporation Coil spring
US11181160B2 (en) * 2016-04-13 2021-11-23 Suncall Corporation Coil spring
US11719298B2 (en) * 2016-04-13 2023-08-08 Suncall Corporation Coil spring

Also Published As

Publication number Publication date
NL7407353A (xx) 1974-12-03
BE815882A (fr) 1974-09-30
CH584367A5 (xx) 1977-01-31
FR2231892A1 (xx) 1974-12-27
AT337501B (de) 1977-07-11
NL163146C (nl) 1980-08-15
NL163146B (nl) 1980-03-17
DK293874A (xx) 1975-01-20
IT1013830B (it) 1977-03-30
DE2327796B2 (de) 1978-01-12
DE2327796A1 (de) 1975-01-09
GB1470076A (en) 1977-04-14
ATA445874A (de) 1976-10-15
JPS5026939A (xx) 1975-03-20
DE2327796C3 (de) 1978-09-28
FR2231892B1 (xx) 1977-03-11
BR7404521D0 (pt) 1975-01-07
JPS5537655B2 (xx) 1980-09-29
SE7407246L (xx) 1974-12-02

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